The overcomplicated chemistry of Sirius Black
by jennygiraffadil
Summary: Remus and Sirius are like oil and water.


**Title:** The severely overcomplicated chemistry of Sirius Black.  
**Pairing:** Remus/Sirius.  
**Disclaimer:** I wish.  
**Summary:** Remus and Sirius are like oil and water. Written for my lovely friend Susanna.

Somewhere, between the arguments and the battle of wills and petty little snipes from across the hall, they're exactly the same. Only, at sixteen, neither of them see it. Sirius is like water - he fits. No matter what the situation he manages to blend, to arch his back and twist his neck and he'smilingbutitfeelssowrong - he can connect, and it doesn't matter who. But to Remus, that's part of the problem.

He takes them all on, every single one, and he strolls back into the common room with a lopsided grin and a head full of bad ideas. "She gets me." he says and they all nod along, "She really gets me." and then the next one comes along. Someone better, someone brighter, but they all understand him. "It's - complicated." Sirius mutters in way of an excuse, "They get different parts of me. And sometimes," his voice softens barely, "--sometimes it feels, I don't know, like we're - bonded. Not exactly. But - it's hard to explain. Like someone is keeping us comfortable, not letting us get any more or less better acquainted."

James calls him crazy then, affectionately, nudging his shoulder and Peter calls him a pansy behind his hand. And they're all laughing - their stomachs aching, but Remus holds back and doesn't quite smile.

_I have a theory,_ he writes in cursive thick black ink - lying flat on his stomach with a parchment creasing at the edges trying desperately to meet in the middle, _and whilst somewhat disproved, I like to believe it._

Remus - Remus is oil and he's always missing out. Digging his way just below everybody's line of sight, of acknowledgement. The stories and the poems, none of them have real endings but he likes them that way; if nothing is permanent, he thinks, it can be changed. The only part of him that disagrees, however, is the seven-year-old boy who still organises his socks by colour and material. Or highlights important points in an essay both with italics and underlining - in case the professor misses them, or perhaps, in case they're something new. Something just for him. He doesn't speak as much as he should, he knows, and he doesn't socialise in the right way. Sometimes, watching his friends - sometimes, watching Sirius, he thinks part of him is missing. And he sits then, perched perfectly still with a quill in his hand, he sits and writes it down.

_Every two people, or three people, they all interact differently. It's nothing to do with personality, but almost everything to do with chemistry._

"Sirius is what?" James scrunches up his face when he tells him, tries to tell him, and it's rational and honest and makessomuchsense. He straightens his shoulders whilst managing to look awkwardly at his feet.

"Sirius is water." he repeats, "He's the solvent. And all of us are solutes."

And in his head it worked. It worked so well he needed a second opinion, he needed to say it outloud, he needed ohgodjust he had to tell someone.

But James snorts and a smirk catches as a throaty sound against his teeth.

"Well he gets all girls wet - apparently. Not to mention his own," he pauses, "--'wet dreams' but...what the fuck? Seriously?"

And Remus shakes his head before Sirius slams the door and they start all over again.

_BASIC CHEMISTRY OF WIZARDS AND MUGGLES_, he writes in capitals, biting his lip before crossing it out. _THE SEVERELY OVERCOMPLICATED CHEMISTRY OF SIRIUS BLACK_ and glancing up as a girl crumples into Sirius's arms quite happily before he shrugs her off for a pair of dark eyebrows hitching across the room, he wonders why he never got it earlier.

"She's not a fucking whore --" and Remus sighs, backed up against the wall off the potions classroom. 

He shakes his head.

"I never said she was." but his lips thin, "I simply stated that maybe your affections are misplaced if you were wanting somebody faithful."

"Fuck you, Lupin." Sirius's hands tighten around his shoulders, his thumbs digging in the hollow between the bones and he almost winces. He'll have indents. He'll have bruises. And then they both look up. 

"Well fuck you, Black."

And for an instant - a fraction of a second when his mind stopped, he almost thought Sirius was about to. That is, until James and Peter showed up and the heady eyes, instead, fell to the skirt of a Hufflepuff or the missing belt loops of a Ravenclaw Prefect.

"You okay?" James asks and he smiles, plucking his robes away from his body, but he walks slowly nonetheless.

"Absolutely fine." 

They didn't mix, they both knew it. They didn't work or fit or - or - love, Remus thought, quickly, desparately, before knocking it back. Oil and Water. But they still danced around it - whatever _'it'_ had turned into. Before, it was getting past a day without a hasty glance or a fight or a blackeye. Now - Remus sighed, _now exactly_.

_'Some, for all the chemistry is potential, amounts to nothing but stagnating opportunity unless the energy can be converted into something slightly more kinetic. There is chemistry, the basic human kind, and 'chemistry' where it's more than just covalent bonds.'_

"Loony Lupin." Sirius hisses under his breath, passing behind him on the way to charms, "Loony loony Lupin."

And the tension creeps up his spine when their bodies nearly touch. Like heat and static.

"Fuck you --" Remus mumbles back, "Nobody likes it doggy style anymore."

He's pushed against the wall but he doesn't fight back, just watches, and his breath hitches.

"You drive me fucking crazy." Sirius breathes against him, "You make me --" and he trails off, he thinks, he sighs, hedoesn'tgetit. But their hips push together anyway, in the middle of the hall, and he can feel the outline of Sirius's jeans beneath his robes. And Sirius's forming erection below them.

"Make you what?" Remus challenges, pushing his stomach up until his thigh catches just offcentre, "Make you -- _what_?" 

His eyes are staring up and his lips are twisted, suddenly, smirking, grinning, almost. But he's hard. And Sirius steps away. Walks away.

"You don't get it." he mutters to himself, trying to smooth the creases between his eyes, "You just -- nevermind."

_Others, it's nothing but desparation. But they try because it hurts not to._

"So - uh -" And Sirius is perched on the edge of Remus's bed. It's dark, but he still sees the way he blinks and tries not to look at him. Tries, instead, to watch the shadows spreading out between his fingertips against the mattress.

"Yeah." Remus whispers, "Um."

And they don't know whether it would be better or worse to go to sleep and forget it all.

"Look, I--" Sirius moves closer, pulling his knees up over the edge and the curtains sway precariously. Remus, thinking, nudging his toes away - and he interrupts.

"Don't start right now I hav-"

And that's when Sirius kisses him.

"Oh."

_You and I are oil and water, just trying to mix it up_


End file.
